Safety device for dishwashing machine



March 26, 1957 B. E. ROBINSON ET AL 2,736,473

SAFETY DEVICE FOR DISK-{WASHING MACHINE Filed Sept. 22, 1953 3 Sheets-Sheet 1 INVENTORS m M R g o A Z 50 2 Z w 0 M.

March 26, 1957 B. E. ROBINSON EFAL 2,786,478

SAFETY DEVICE FOR DISHWASHING MACHINE Filed Sept. 22, 1953 3 Sheets-Sheet 2 v f Z g 1Z2 IN VEN TORS EFOC! a. ,POA/A/JO/Y i440 4 066297 0. aflazm March 26, 1957 B. E. ROBINSON EIAL 2,786,478

SAFETY DEVICE FOR DISK-{WASHING MACHINE Filed Sept. 22; 1953 3 Sheets-Sheet 3' 22 f% H 25 5 /2 n C Eh/j WA SH M0 TOR &[| I

WA SH MO TOR United States Patent SAFETY DEVICE FOR DISHWASHING MACHINE Bruce E. Robinson and Robert 0. Bradley, Toledo, Ohio, assignors to Toledo Scale Company, Toledo, Ohio, a corporation of New Jersey I Application September 22, 1953, Serial No. 381,541

12 Claims. (Cl. 13458) This invention relates to dishwashing machines, and in particular to a safety device for preventing scalding of an operator by hot water during operation of the dishwashing machine.

In a commercial type dishwasher such as is used in restaurants, cafeterias, hospitals, kitchens, etc. it is customary to finally rinse dishes with extremely hot water which serves not only to rinse the dishes but also to sterilize them. If during the operation of the rinsing mechanism the door of the dishwashing machine is accidentally opened by the operator, hot rinse water is sprayed out into the open and can easily scald the operator.

The principal object of this invention is to prevent injury to an operator of a dishwashing machine when the door of the machine is accidentally opened during a washing or rinsing operation.

Another object of the invention is to provide means which upon opening of the door of the dishwashing machine, disrupts operation of the mechanism of the machine and prevents further operation thereof.

More specifically, it is an object of the invention to provide a safety switch on the frame of the machine and switch-operating means on the door of the machine which last-named means operates the safety switch to permit operation of the machine when the door is closed and prevent operation of the machine when the door is open.

Other objects and advantages will be apparent from the following description in which reference is had to the accompanying drawings.

According to the invention, a safety switch mounted on the frame of the machine is engaged by switch-operating means on the door of the machine. The switch closes whenever the door is closed and opens whenever the door is raised. If the machine is in operation when the door is raised, the switch automatically disrupts the operation of the machine and prevents further operation while the door remains raised.

In the drawings:

Figure I is a perspective view of a dishwashing machine embodying the invention.

Figure II is a plan view of a switch and switch-operating means taken substantially along lines IIH of Figure I.

Figure III is a fragmentary elevational view taken substantially along lines IIIIII of Figure II.

Figure IV is a simplified isometric view of the switch and switch-operating means.

Figure V is an electrical wiring diagram of the control system of the preferred form of the invention.

Figure V1 is an electrical wiring diagram of the control system of a modification of the invention.

These specific figures are intended merely to illustrate the invention but not necessarily to limit its scope.

Referring to Figure l, a frame 1 has a washing space 2 thereabove enclosed by a vertically movable threesided door or closure 3. The door 3 is raised or lowered by an operator grasping a handle 4 and sliding the door up or down. The door has its two forward corners guided by posts 5 and its two rearward vertical edges guided in channels 6. A counterweight 7 is operatively "ice connected to the door 3 by means of a pulley system (not shown) to facilitate raising and lowering the door 3.

Below the washing space 2 is a tank which contains wash water which is sprayed onto dishes placed in the washing space 2 through spray tubes 8. The water from the tank goes to a pump 9 operated by an electric motor to force Water under pressure through the spray tubes 8. A plurality of the spray tubes are provided at both the bottom and the top of the washing space in the usual manner.

Additional spray tubes 8a, the upper ones of which are shown, are provided above and below the washing space to supply hot rinse water from a fresh water supply directly onto the dishes for rinsing and sterilizing the dishes. Control of the rinsing operation is accomplished by an electrically-operated solenoid valve 10 in the hot water line.

Operation of the washing and rinsing devices is effected by pushing a wash button 11 and a rinse button 12 mounted on a control box 13 located at the right side of the frame 1.

Referring now to Figures II and Ill, a sleeve 13a having a large head 13b is rigidly attached to the frame 1 by means of a nut 130. The large head 13b is separated from the frame 1 by a gasket 13d preventing leakage of water through the frame around the sleeve 13a. A pivotal shaft 15 turns in a long drilled hole within the sleeve 13a and carries a counterweighted arm 14 adapted to have a portion thereof engaged by the door 3 whenever the door is in closed position and a Z-shaped finger 16 which finger 16 is attached to the pivotal shaft 15 through a cut 150 in the sleeve 13a and prevents disengagement of the pivotal shaft 15 from the drilled hole of the sleeve 13a. The control box 13 is rigidly attached to an end of the sleeve 13a through an L-shaped bracket v 20 joined to the sleeve 13a by means of a stud 29a and a nut 21.

Pivotal movement of the shaft 15 in response to engagement of the arm 14 by the door 3 causes the Z- shaped finger 16 mounted on the shaft 15 to engage a finger 17 of a safety switch 18 to close the switch and the circuit to the control mechanism within the control box 13. Whenever the door is raised, a counterweight 19 on the arm 14 pivots the arm 14 and the shaft 15 back to the position whereby the Z-shaped finger 16 no longer engages the finger 17 of the safety switch 18 to close the switch.

Referring now to Figure IV, the arm 14, finger 16, and shaft 15 are pivoted from positions shown in solid lines whenever the door is open to positions shown in dotted lines whenever the door is closed and the bottom of the door engages a rounded portion of t e counterweighted arm 14. The safety switch 18 is wired in series with the control mechanism in a manner such that operation of the washing and rinsing cycles is permitted only when the contacts of the safety switch 18 are closed, as by engagement of the Z-shaped finger 16 with the finger 17 of the switch when the door 3 is in down or closed position.

In the preferred embodiment of the invention the operation is as follows: With the door closed, the wash button 11 is depressed and immediately released. This starts the wash motor to operate the pump 9 to spray wash water from the tank through the spray tubes 8 onto dishes placed in the washing space 2. There is a washing solution in the wash water to permit effective washing of the dishes after a suitable time period has elapsed during which the operation of the washing continues, the rinse button 12 is depressed and the control mechanism for pumping wash water through the spray tubes 8 is automatically shut off. The rinse button 12 must be held in throughout the rinse period, because upon release of the rinse button 12 the rinsing mechanism is shut off. The purpose of this is that the rinse cycle should take place for only about ten seconds. During this time an effective rinsing and sterilizing action takes place. it is undesirable to let the rinsing continue for any great length of time since the rinse water as it drains from the dishes enters into the wash tank and dilutes the wash water. Too long of a rinse would mean that too much washing solution would be needed for washing. Frequent additions of solution to the Wash water in the tank would therefore be necessary.

It should be understood that the operation just described can take place only when the door is closed so as to engage the counterweighted arm 14 which causes the shaft to pivot the finger 16 and engage the finger Ti? to close the switch 18. If the door were up or opened and either of the buttons 11 or 12 would be depressed, the washingor rinsing mechanism would be inoperative.

Electrical operation of the dishwashing machine is as follows. in Figure V which illustrates the preferred form of the. invention, the door must be in enclosing position of a Washing space 2 so as to pivot the Z-shaped finger 16 to cause the finger 17 to close the safety switch 13. With the safety switch 1% closed, the wash button lli is depressed to cause current to fiow through the lead 22 to a branch lead 23, through the safety switch 13, through the rinse button 12, through the wash button 11, to the coil of a relay 2%, then to the opposite side of the line. Energization of the relay 24 closes its contacts and 26. Closing of the contacts 25 permits electrical current to by-pass the wash button 11 to maintain the relay 24 energized when the button 11 is released. Closing of the contacts 26 energizes the wash motor and causes the pump 9 operated by the wash motor to spray wash water from the tank into the washing space 2 under pressure through the spray tubes 8. The washing operation continues until the operator depresses the rinse button 12. Depression of the button 12 opens its upper contacts to break the circuit through the branch lead 27 to the relay 24. This opens the contacts 25 and 26. Opening of the contacts 26 prevents further operation of the wash motor and the washing cycle is completed. Closing of the lower contacts 28 of the rinse button 12 permits current to flow through the lead 23, the safety switch 8, a lead 29, through the contacts 28, and then to the coil of the rinse solenoid valve in to energize the solenoid and open its valve. Opening of the valve it! permits water to flow through the hot water line 3% under normal pressure through the rinsing tubes and onto the dishes. The rinse button 12 must be maintained depressed for the desired rinsing period, and upon release of the button 12 it is returned to its original position to break the contacts 28 and disrupt the circuit passing through the solenoid valve It). The rinse operation is therefore completed. The door 3 may then be raised and dishes removed from the washing space 2.. If, at any time during the operation of the washing or rinsing mechanism, the door is raised, the Z-shaped finger 16 will pivot with the shaft 15 in response to the pivotal movement of the arm 14 by the counterweight 19 to release the finger 17 of the switch 18 and open the safety switch. Opening of the safety switch 18 breaks the flow of current through the lead 23 and prevents operation of the wash motor or the solenoid valve 10. As long as the door is raised, the wash button 11 or rinse button 12 may be depressed without causing operation of the washing or rinsing mechanism. The only possible way the machine can be operated when the door is raised is to pivot the counterweighted arm 14 downwardly and depress either of the buttons at the same time. To accidentally do this would be practically impossible. An operator can therefore place a rack of dishes into the washing space or remove them therefrom without any fear of the machine starting to operate and spraying scalding water. The counterweighted arm may even be accidentally moved, but this itself will not start operation of the machine. Likewise, the buttons 11 and 12 may be accidentally depressed but this again would not cause operation of the washing or rinsing mechanism unless the M- is pivoted downwardly at the sme time.

The wiring diagram illustrated in Figure VI is sub stantially similar to that shown in Figure V with the exception that a stop button has been added to the control system. In this modification, a rinse button 12a may be released as soon as it is depressed and a stop button 31 must be depressed to shut off the rinse operation. As before, opening of the safety switch 18 by raising the door 3 during the operation of either the washing or rinsing mechanism automatically shuts ofi the current supplied to either the washing or rinsing mechanism. Depression of a wash button llla energizes a relay 2%. Energization of the relay 24a closes contacts 25a and 26a to shunt current around the wash button 11a through a lead 27a to the coil of the relay 24a, and to operate the wash motor as in the preferred embodiment of the invention to commence the washing operation.

The washing operation continues until the rinse button 12a is depressed to open its upper contacts and cut off the current supplied to the relay 24a and to close its lower contacts 28a to supply current to the solenoid valve 19a through the lead 2%. This energizes the coil of the solenoid valve 16a to operate the valve and permit hot water to pass through a hot water line 30a. Simultaneously with the energization of the solenoid valve 16a, a relay 32 is energized to close its contacts 33 and shunt current to the relay 32 around the lower contacts 28a of the rinse button 12a. The rinse button 12a may then be released and the solenoid valve Ma and relay 32 are maintained energized by current flowing through the lead 29a and the contacts 33. After a suitable period of time has elapsed during which the rinsing operation takes place, the stop button 31 is depressed to cut elf current supplied to the relay 32 and the solenoid valve 10a. The washing and rinsing is now completed and the operator may remove the cleaned dishes from the washing space 2. If the safety switch 13a is opened at any time during the operation, the power to the washing and rinsing mechanism is automatically cut off and further operation is prevented until the door is again closed.

Various modifications and changes in the details of construction may be made without departing from the spirit and scope of the invention.

Having described the invention, we claim:

1. In a dishwashing machine, in combination, a frame having a washing space thereabove, a closure cooperating with said frame to enclose or expose said washing space, washing mechanism including spray tubes within said washing space adapted to have wash. water conducted therethrough from a supply source, a control box spaced apart from said frame, control means for said washing mechanism, a movable arm that is rockably mounted on said frame within said washing space and that is engageable by said closure when said closure encloses said washing space, a finger that is operatively connected to said arm and that is located outside of said washing space, and a safety switch located in said control box and operated by said finger and being adapted, whenever said closure is moved to exposing position, to disrupt and prevent the operation of said washing mechanism by said control means.

2. In a dishwashing machine, in combination, a frame having a washing. space thereabove, a closure cooperating with said frame to enclose or expose said washing space, washing mechanism including spray tubes within said washing space adapted to have wash water conducted therethrough from a supply source, control means for said washing Lechanism, a movable cotmterweighted arm that is rockably mounted on said frame within said washing space and that is engageable by said closure when said closure encloses said washing space, a finger that is operatively connected to said arm and that is located outside of said washing space, and a safety switch operated by said finger and being adapted, whenever said closure is moved to exposing position, to disrupt and prevent the operation of said washing mechanism by said control means.

3. In a dishwashing machine, in combination, a frame having a washing space thereabove, a closure cooperating with said frame to enclose or expose said washing space, washing mechanism including spray tubes within said washing space adapted to have wash water conducted therethrough from a supply source, a control box spaced apart from said frame, control means for said washing mechanism, a sleeve extending through said frame, a shaft pivotally mounted within said sleeve, an arm on the end of said shaft within said washing space and engageable by said closure when said closure encloses said washing space, a finger on said shaft outside of said washing space, and a safety switch located in said control box and operated by said finger and being adapted, whenever said closure is moved to exposing position, to disrupt and prevent the operation of said washing mechanism by said control means.

4. A dishwashing machine according to claim 3 wherein the sleeve is provided with a slot and the finger is located in the slot whereby the finger functions additionally to retain the shaft within the sleeve.

5. In a dishwashing machine, in combination, a frame having a washing space thereabove, a closure cooperating with said frame to enclose or expose said washing space, washing mechanism including spray tubes within said washing space adapted to have wash water conducted therethrough from a supply source, control means for said washing mechanism, a sleeve extending through said frame, a shaft pivotally mounted within said sleeve, a counterweighted arm on the end of said shaft within said washing space and engageable by said closure when said closure encloses said washing space, a finger on said shaft outside of said washing space, and a safety switch operated by said finger and being adapted, whenever said closure is moved to exposing position, to disrupt and prevent the operation of said washing mechanism by said control means.

6. A dishwashing machine according to claim 5 wherein the sleeve is provided with a slot and the finger is located in the slot whereby the finger functions additionally to retain the shaft within the sleeve.

7. In a dishwashing machine, in combination, a frame having a washing space thereabove, a closure cooperating with said frame to enclose or expose said washing space, washing mechanism including spray tubes within said washing space adapted to have wash water conducted therethrough from a supply source, rinsing mechanism including spray tubes within said washing space adapted to have rinse water conducted therethrough from a rinse water supply source, a control box spaced apart from said frame, means for independently controlling the operation of said washing mechanism and said rinsing mechanism, a movable arm that is rockably mounted on said frame within said washing space and that is engageable by said closure'when said closure encloses said washing space, a finger that is operatively connected to said arm and that is located outside of said washing space, and a safety switch located in said control box and operated by said finger and being adapted, whenever said closure is moved to exposing position during operation of either said washing or rinsing mechanism, to disrupt and prevent further operation of said washing or rinsing mechanism.

8. In a dishwashing machine, in combination, a frame having a washing space thereabove, a closure cooperating with said frame to enclose or expose sai-d washing space, washing mechanism including spray tubes within said washing space adapted to have wash water conducted therethrough from a supply source, rinsing mechanism including spray tubes within said washing space adapted to have rinse water conducted therethrough from a rinse water supply source, means for independently cont-rolling the operation of said washing mechanism and said rinsing mechanism, a movable counterweighted arm that is rockably mounted on said frame within said washing space and that is engageable by said closure when said closure encloses said washing space, a finger that is operatively connected to said arm and that is located outside of said washing space, and a safety switch operated by said finger and being adapted, whenever said closure is moved to exposing position during operation of either said washing or rinsing mechanism, to disrupt and prevent further operation of said washing or rinsing mechanism.

9. In a dishwashing machine, in combination, a frame having a washing space thereabove, a closure cooperating with said frame to enclose or expose said Washing space, washing mechanism including spray tubes within said washing space adapted to have wash Water conducted therethrough from a supply source, rinsing mechanism including spray tubes within said washing space adapted to. have rinse water conducted therethrough from a rinse water supply source, a control box spaced apart from said frame, means for independently controlling the operation of said washing mechanism and said rinsing mechanism, a sleeve extending through said frame, a shaft pivotally mounted within said sleeve, an arm on the end of said shaft within said washing space and engageable by said closure when said closure encloses said washing space, a finger on said shaft outside of said washing space, and a safety switch located in said control box and operated by said finger and being adapted, whenever said closure is moved to exposing position during operation of either said washing or rinsing mechanism, to disrupt and prevent further operation of said washing or rinsing mechanism.

10. -A dishwashing machine according to claim 9 wherein the sleeve is provided with a slot and the finger is located in the slot whereby the finger functions additionally to retain the shaft within the sleeve.

11. In a dishwashing machine, in combination, a frame having a washing space thereabove, a closure cooperating with said frame to enclose or expose said washing space, washing mechanism including spray tubes Within said washing space adapted to have wash water conducted therethrough from a supply source, rinsing mechanism including spray tubes within said washing space adapted to have rinse water conducted therethrough from a rinse water supply source, means for independently controlling the operation of said washing mechanism and said rinsing mechanism, a sleeve extending through said frame, a shaft pivotally mounted within said sleeve, a counterweighted arm on the end of said shaft within said washing space and engageable by said closure when said closure encloses said washing space, a finger on said shaft outside of said washing space, and a safety switch operated by said finger and being adapted, whenever said closure is moved to exposing position during operation of either said washing or rinsing mechanism, to disrupt and prevent further operation of said washing or rinsing mechanism.

12. A dishwashing machine according to claim 11 wherein the sleeve is provided with a slot and the finger is located in the slot whereby the finger functions additionally to retain the shaft within the sleeve.

References Cited in the file of this patent UNITED STATES PATENTS 

